Technical Field
This disclosure relates to a sheet feeder that is attached to a copier, facsimile machine, printer, printing machine, and a multi-functional apparatus including at least two functions of the copier, facsimile machine, printer, and printing machine to separate and feed a sheet-like recording medium, and an image feeding apparatus and an image reading device incorporating the sheet feeder.
Related Art
Sheet conveyance (conveyability of sheets) is one of qualities of an image forming apparatus such as a copier, facsimile machine, printer and the like. In recent years, various types of sheets are used in an image forming apparatus, and therefore it is indispensable to enhance quality of feed and separation of sheets. RF (roller friction) feeding system and FRR (feed and reverse roller) feeding system are known as a sheet feeder that perform high quality feed and separation of sheets.
Indeed, the RF feeding system and the FRR feeding system can provide a high quality performance in feed and separation of sheets. However, these systems cannot reduce both costs and size of the image forming apparatus.
By contrast, a separation pad feeding system (also known as a friction pad feeding system) is known as a relatively reasonable and compact sheet feeder.
The separation pad feeding system includes a receiver having a friction member, i.e., a separation pad below a sheet feed roller. The separation pad feeding system causes a sheet fed by the sheet feed roller to contact the separation pad, so that multifeed of sheets is prevented due to friction between the separation pad and the sheet. According to this action, a single sheet contacting the sheet feed roller, which is an uppermost sheet, is separated from the other sheets in a sheet container and fed toward an image forming part.
The separation pad is formed by a material having a friction coefficient smaller than that of the sheet feed roller. For example, the separation pad is formed from a single member made of natural rubber, cork, leather, urethane rubber, synthetic rubber or the like.